Sunday, December 8, 2013

Chinese Breast Cancer Trends

The latest meta-analysis from China shows that breast cancer is 44% more likely among Chinese women who have had one or more abortions. Critics claim this study is flawed because it relies on "case-control studies" which match a woman with cancer to a woman without cancer. The "recall bias" theory holds that women with cancer tend to tell the truth about their abortion history, while healthy women tend to conceal their abortions--even in China, where abortion is anything but "a private matter between a woman and her doctor."

It is easy to put the recall bias theory to the test. China has traditionally had a low breast cancer rate (only one out of forty Chinese women expect to get the disease, a mere fraction of the American rate). If abortion does not increase the risk of breast cancer, tens of millions of Chinese abortions should have no impact on cancer incidence in China. But breast cancer in China is rising, and rising rapidly, as this public service simulation from General Electric shows.

This could be mere coincidence. Logicians recognize the post hoc ergo propter hoc fallacy--"after something, therefore because of something." There could be other causes of China's rising cancer rate. Oral contraceptives are known to have carcinogenic effects--but less than 2% of Chinese women have access to the Pill.

Perhaps pollutants are causing the increase. When the pesticide DDT breaks down to DDE, it mimics some of the effects of estrogen, leading some researchers to suspect it as a cause of cancer. China used to use DDT extensively in agriculture. If DDT caused breast cancer, one would expect peasant women in China to have elevated rates, while urban women might be spared. If abortion increases the risk of cancer, the results should be the opposite, because urban women in China are more likely to abort than peasant women are. As it turns out, breast cancer rates are rising more rapidly among urban women in China than among peasants.

Something is causing Chinese breast cancer cases to rise. It isn't the Pill, and it isn't DDT. What, then?

The latest meta-analysis says that women who choose abortion are 44% more likely to get breast cancer than do those that don't. Multiply that small number by millions and you get exactly what China is now experiencing--a rise in breast cancer all over the country with the highest rates in the urban centers.